Ganglion

/ˈgaNGglēən/

Noun, pl. ganglia

(Anatomy)
1. A biological tissue mass, most commonly a mass of nerve cell bodies. Cells found in a ganglion are called ganglion cells, though this term is also sometimes used to refer specifically to retinal ganglion cells. (wikipedia.org)

2. A mass of tissue. (wikipedia.org)

3. A benign cyst found on aponeurosis or tendon, usually at the wrist or dorsum of the foot. (biology-online.org)

4. A structure containing a number of nerve cell bodies, typically linked by synapses, and often forming a swelling on a nerve fiber. (Google Dictionary)